Project Summary/Abstract The suffering caused by Alzheimer?s disease (AD) remains one of the greatest unmet medical needs of our times. With a heightened sense of urgency, numerous AD prevention trials are being launched, requiring an unprecedented number of healthy older adults to be screened to identify the thousands eligible to participate. Recognizing this obstacle, initiatives such as the National Plan to Address AD call for greater attention to 1) increasing enrollment into clinical trials and other clinical research, and 2) monitoring and identifying strategies to increase enrollment of racial and ethnic minorities in AD studies. An outgrowth of the National Plan is the National Strategy for Recruitment and Participation in Alzheimer's Disease Clinical Research which recognizes the requirement for developing and understanding a new ?science of recruitment.? Recently, multiple AD recruitment registries have been developed, including but not limited to the Alzheimer?s Prevention Registry, GeneMatch, the Brain Health Registry, and GenePool. Although each differs in what they require of participants in terms of information and time commitment (herein referred to as ?tiers of participation?), the registries share a common goal of accelerating enrollment into AD studies. However, despite enrolling >450,000 across all four registries, enrollees in each registry are predominantly female and non-Hispanic / white, thereby perpetuating the lack of diversity among AD prevention trial participants. The objective of this proposal is to understand how to effectively communicate the importance of AD prevention trial participation to men and minorities. This proposal will accomplish this objective via the following aims: 1) using semi-structured interviews and a nationally representative survey to identify the relevant psychosocial determinants (attitudes, norms, efficacy/control) for each ?tier of participation? and understanding how they vary by race/ethnicity and gender; 2) develop and test evidence-based messaging to join each registry via iterative concept testing via focus groups enriched for men and minorities and online message testing to assess persuasiveness, and 3) deploy evidence-based messages into our real-word testing environment, measuring their impact on enrollment of men and minorities into each registry and enrollees? subsequent willingness to participate in AD prevention trials. We hypothesize that enrollment of men and minorities into each registry will increase, with positive downstream effects on diversity among AD prevention trial participants.